6-hydroxy chromans used as stabilizing agents in a color photographic element



United States Patent 3 432,300 G-HYDROXY CHROli'IANS USED AS STABILIZ- ING AGENTS IN A COLOR PHOTOGRAPHIC ELEMENT Gregory J. Lestina and Warren A. Reckhow, Rochester,

N.Y., assignors to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey No Drawing. Filed May 3, 1965, Ser. No. 452,889 U.S. Cl. 9674 14 Claims Int. Cl. G03c 7/18, 7/00 ABSTRACT OF THE DISCLOSURE Dye stabilizing quantities of 6-hydroxy chroman characterized by having an alkyl group on one of the two positions ortho to the hydroxy, and hydrogen on the other ortho position, as well as on the meta position of the benzene ring of said compound are advantageously incorporated in hydrophilic colloid layers in which color photographic dye images are to be formed or to which ditfusible dye images are to be transferred so that the 6-hydroxy chroman is contiguous to the dye image that is to be stabilized. Photographic elements containing the immediate 6-hydroxy chromans are processed without producing unwanted light absorption produced by the stabilizing agents outside of the invention and provide considerable improvement inthe light stability of the image dyes in the layer containing the stabilizing agent.

This invention relates to color photography and color photographic materials, and more particularly to improved color photographic materials containing new dye image stabilizing agents, new methods for improving the stabilities of image dyes in color photographic materials and new ballasted dye image stabilizing agents.

The formation of dye images by the chromogenic development of silver halide photographic materials, involving the coupling reaction of oxidized primary aromatic amino developing agents with coupling compounds to form indophenol, indamine, azomethine, phenoxazine, phenazine, and similar dyes, is well known. In this system, the subtractive color process of color formation is ordinarily used and the image dyes customarily formed are cyan, magenta, and yellow, which are the colors that are complementary to the primary colors red, green and blue, respectively. Usually phenolic couplers (i.e., phenols and naphthols) are used to form the cyan dye image; pyrazolone or cyanoacetyl couplers are used to form the magenta dye image; and acylacetamide or dibenzoylmethane couplers are used to form the yellow dye image.

In these color photographic systems, the color-forming coupler may be applied in a developer solution or incorporated in the light-sensitive photographic emulsion layer or in another dye-image-forming layer, so that, during development, it is available to react with oxidized color developing agent formed as the result of latent image development.

The dye images formed in such processes are not indefinitely stable to ultraviolet radiation so that under rigorous viewing or display condition involving, for example, long periods of exposure to sunlight, or other ultraviolet radiant illumination, the dyes may fade, result ing in deterioration in the quality of the picture.

Increases in the stability of indophenol, indoaniline, and

azomethine dyes to ultraviolet radiation have been achieved by the use of a variety of agents which can be added to the emulsion in processing, or more conveniently, in manufacture. The need remains for further enhancement of the resistance of these dyes to actinic light and, indeed, this requirement is increasing as recent and continuing technological improvements in the durability of the photographic layers and supports are making practical the use of prints in exposed locations, indoors and out, which would have been unthinkable a few years ago.

It is, therefore, an object of our invention to provide new and improved compounds for increasing the stability to ultraviolet and visible light radiation, of the image dyes used in color photography.

It is a further object of our invention to provide new and improved image-dye-stabilizing agents which are compatible with and nonditfusing in the hydrophilic colloid layers in which they are incorporated.

It is a further object of our invention to provide new and improved image-dye-stabilizing agents which do not form highly colored oxidation products in the processing baths, such as bleach bath, etc., used in color photographic processing.

It is another object of our invention to provide color photographic image-forming layers comprising hydrophilic colloidal film-forming binders containing finely particulate dispersions of solutions of our new stabilizing agents.

It is a further object to provide such layers also containing couplers.

It is a further object of our invention to provide photographic silver halide-gelatin emulsion layers containing dispersions of couplers and our new and improved stabilizing agents.

It is still another object of our invention to provide dispersions of our new and improved stabilizer compounds which can be incorporated in silver halide emulsions without adverse emulsion effects.

It is still a further object to provide processed color photographic layers containing dye images in association with the new stabilizing compounds of our invention.

These and other objects of our invention are achieved by addition to layers intended for the preparation of color photographic dye images, of dye-stabilizing quantities of G-hydroxy chromans (chroman-G-ols), characterized by having an alkyl group on one of the two positions ortho to the hydroxy, and hydrogen on the other ortho position, as well as on the meta position of the benzene ring in said compound, so the 6-hydroxy chroman is contiguous to the dye image that is to be stabilized.

Particularly beneficial dye-stabilizing agents for the practice of our invention are found in the class of chroman-6-ols (or 6-hydroxy chromans) of the formula:

The R groups on the above formula may be hydrogen or alkyl, particularly alkyl of from 1 to 18 carbon atoms.

One of the R and R groups is an alkyl group, the other is hydrogen. The alkyl groups can be straight, branched chain or cyclic. The number of individual alkyl groups, and their respective size, is determined by the resistance to diffusion and the solubility characteristics required. Cycloalkyl groups, such as cyclohexyl, cyclopentyl, etc., are used as substituents, although the preferred substituents will be simple alkyl groups, e.g., methyl, isopropyl, t-butyl, t-octyl, n-octadecyl, etc., and one or more of these alkyl groups may be substituted, for example, with such groups as hydroxyl, halogen, carboxyl, carbalkoxy, acyloxy (e.g., acetoxy), sulfo, sulfonyloxy, amido (e.g., acetamido, ethylsulfonamido, benzamido, etc.), and an ether group, e.g., alkoxy (such as, methoxy, butoxy, dodecyloxy, etc.), aryloxy (such as, phenoxy, naphthoxy, etc.).

The following examples of the new and improved stabilizing agents of our invention are used to illustrate but not limit our invention.

( 1) 2,2-dimethyl-4-isopropyl-6-hydroxy-7-t-butylchroman,

(2) 2,2,4-trimethyl-6-hydroxy-7-t-butylchroman,

(3) 2,2,4-trimethyl-6-hydroxy-7-isopropylchrornan,

(4) 2,2-dimethyl-4,7-di-isopropyl-6-hydroxychroman,

(5) 2,2-dimethyl-6-hydroxy-7-t-butylchroman,

(6) 2,2-dimethyl-4-isopropyl-6-hydroxy-7-t-octylchroman,

(7) 2,2,4-trimethyl-6-hydroxy-7-t-octylchroman,

(8) 2-methyl-2-n-octyl-4- fi-carbomethoxybutyl -6 hydroxy-7-t-butylchroman,

(9) 2-methyl-2-n-octyl-4-(fi-carboxy-butyl)-6-hydroxy- 7-t-butylchroman,

(10) 2-methyl-2-n-octyl-4-[5-(N-methylcarbamyl)- butyl]-6-hydroxy-7-t-butylchroman,

(1 l) 2-(8-methoxybutyl)-2-methy l-4-hexadecyl-5-ethyl- 6-hydroxychroman,

(12) 2,2-dimethyl-4-(w-chlorononyl)-6-l1ydroxy-7-tbutylchroman,

( 13 2,2-dimethyl-4-(w-hydroxyoctyl -6-hydroxy-7-nhexylchroman,

(14) 2-met-hyl-2-n-octyl-4-[6-(N-phenylcarbamyl)- butyl] -6-hydroxy-7-t-butylchroman.

Our stabilizing agents are used to advantage in improving the stability of the indophenol, indoaniline and azomethine image dyes such as those produced by chromogenic development. Typical examples are the dyes derived from any of the commonly used cyan, magenta, and yellow-forming couplers, by coupling with any of the oxidized primary aromatic amine color developing agents used in color photographic processing. Typical couplers may be found, for example, in the following U.S. patents:

Cyan: 2,895,826, Salminen et al., July 21, 1959; 2,474,- 293, Weissberger et al., June 28, 1949; 2,908,573, Bush et al., Oct. 13, 1959.

Magenta: 2,600,788, Loria et al., June 17, 1952; 2,908,- 573, Bush et al., Oct. 13, 1959.

Yellow: 2,875,057, McCrossen et al., Feb. 24, 1959; 2,908,573, Bush et al., Oct. 13, 1959.

The above references serve to illustrate but not limit our invention. The specific method used to form the indophenol, indoaniline, or azomethine dye image is not important.

Our nondiffusible stabilizing agents are incorporated in the layer which will contain the final dye image. They can be used to advantage in any or all of the emulsion layers of a color film. They can be incorporated either alone or with couplers. A useful method of dispersing our stabilizing compounds is that described for dispersing couplers in Mannes et al., U.S. Patent 2,304,939, issued Dec. 15, 1942; Jelley et al., U.S. Patent 2,322,027, issued June 15, 1943; etc., in Which high-boiling organic solvents are used to dissolve the material. Other applicable methods are described in Vittum et al., U.S. Patent 2,801,170, and

4 Fierke et al., U.S. Patent 2,801,171, both issued July 30, 1957, and Julian U.S. Patent 2,949,360, issued August 16, 1960, in which low-boiling or water-soluble organic solvents are used with high-boiling solvent.

In these methods of dispersion our stabilizing agents can be contained in the same dispersion with nondifiusing couplers, or in a separate dispersion, and the couplers can optionally be dispersed directly in the emulsion. Highboiling solvents useful in dispersing the 6-hydroxy chromans of our invention include di-n-butylphthalate, benzylphthalate, triphenyl phosphate, tri-o-cresyl phosphate, diphenyl mono-p-tert-butylphenyl phosphate, monophenyl di-p-tert-butylphenyl phosphate, diphenyl mono-ochlorophenyl phosphate, monophenyl di-o-chlorophenyl phosphate, tri-p-tert-butylphenyl mono(5-tert-butyl-2 phenylphenyl)-phosphate, 2,4-di-n-amylphenol, 2,4-di-tamylphenol, N,N-diethylauramide, etc.

The low-boiling or water-soluble organic solvents which can be used to advantage with the high-boiling solvents are disclosed in patents, such as Fierke et al., U.S. Patent 2,801,171, and Vittum et al., U.S. Patent 2,801,170, both issued July 30, 1957, and Julian U.S. Patent 2,949,360, issued Aug. 16, 1960, etc.

The organic solvents include:

(1) Low-boiling, substantially water-insoluble organic solvents, such as methyl, ethyl, propyl, and butyl acetates, isopropyl acetate, ethyl propionate, sec-butyl alcohol, ethyl formate, butyl formate, nitromethane, nitroethane, carbon tetrachloride, chloroform, etc., and

(2) Water-soluble organic solvents, such as methyl isobutyl ketone, )9-ethoxyethyl acetate, fi-butoxy, tetrahydrofurfuryl adipate, Carbitol acetate (diethyleneglycol monocetate), methoxytriglycol acetate, methyl Cellosolve acetate, acetonyl acetone, diacetone alcohol, butyl Carbitol, butyl Cellosolve, methyl Carbitol, methyl Cellosolve, ethylene glycol, diethylene glycol, dipropylene glycol, acetone, methanol, ethanol, acetonitrile, dimethylformamide, dioxane, etc.

Combinations of two or more of the new and improved dye-stabilizing agents of our invention may be used. These agents may also be used in combination with other addenda in the same dispersion, for example, other stabilizing agents, antistain agents, e.g., ball'asted hydroquinones, phenolic antioxidants, etc. The selection of the specific stabilizer compound and the concentration used in each layer of a multilayer film can be varied over a wide range, and will depend on the improvement in resistance to fading required for each of the image dyes in the respective layers.

Any of the well known primary aromatic amino colorforming silver halide developing agents such as the phenylenediamines, e.g.,

N,N-diethyl-p-phenylenediamine hydrochloride, N-monomethylp-phenylenediamine hydrochloride, N,Ndimethyl-p-phenylenediamine hydrochloride, 2-amino-5-diethy1aminotoluene hydrochloride, Z-amino-S-(N-ethyl-N-laurylamino)toluene, N-ethyl-N-fl-(methylsulfonamido)ethyl-3-methyl-4- aminoaniline sulfate, N-ethyl-N-(B-methylsulfonamidoethyl)-4-aminoaniline, 4-(N-ethyl-N-[i-hydroxyethyl)aminoaniline, etc.,

the p aminophenols and their substitution products where the amino group is unsubstituted, e.g., 2,6-dichloro- 4-aminophenol, 2-bromo-p-aminophenols, 2,6-diiodo-4- aminophenol, 4-aminophenol, etc., may be used to develop photographic coatings containing our stabilizers. Various other materials may be included in the developer solutions depending upon the particular requirements, for example, image-forming couplers, competing couplers, antifoggants, hardeners, an alkali metal sulfite, bisulfite, alkaline buffer salts, bromide, iodide, etc., and the thickening agents used in viscous developer compositions. A typical developer solution is given in Example 1, but does not limit the invention.

Our stabilizers are incorporated in hydrophilic colloid layers intended for the preparation of photographic dye images, such as, a receiving sheet for receiving a diifusible transferred dye image or a dye-image forming layer containing a light-sensitive material such as silver halide (e.g., silver chloride, silver bromide, silver iodide, silver chlorobromide, silver chlorobromiodide, silver bromoiodide, etc.), ZnO, ZnS, CdS, CdSe, NiS, etc.

Hydrophilic colloids used to advantage in the image layers include any of the hydrophilic colloids used in image-forming layers and in receiving layers, such as gelatin, and gelatin derivatives, casein and other proteinaceous colloids, hydrophilic cellulosic derivatives, e.g., carboxymethyl cellulose, lalgin-ates, synthetic resins, e.g., polyvinyl alcohol, copoly(ethyl-acrylate, acrylic acid) polyvinyl pyrrolidone, etc. Some colloids used to advantage are polyvinyl alcohol or a hydrolyzed polyvinyl acetate as described in US. Patent 2,286,215, a far hydrolyzed cellulose ester, such as cellulose acetate hydrolyzed to an acetyl content of 19-26%, as described in US. Patent 2,327,808, a water-soluble ethanolamine cellulose acetate as described in US. Patent 2,322,085, a polyacrylamide having a combined acrylamide content of 30-60% and a specific viscosity of 025-15 on an imidized polyacrylamide of like acrylamide content and viscosity as described in US. Patent 2,541,474, zein as described in US. Patent 2,563,791, a vinyl alcohol polymer containing urethane carboxylic acid groups of the type described in U.S. Patent 2,768,154, or containing cyano-acetyl groups, such as the vinyl alcohol-vinyl cyano-acetate copolymer as described in US. Patent 2,808,331, or a polymeric material which results from polymerizing a protein or a saturated acylated protein with a monomer having a vinyl group as described in US. Patent 2,852,382.

The emulsions used in the photographic element of our invention can be chemically or optically sensitized.

The stabilizers of our invention may also be used to advantage in image-forming layers, either alone or with image-forming compounds other than silver halide, such as ZnO, ZnS, CdS, CdSe, NiS, etc., with binders such as gelatin, polyvinyl alcohol, etc.

Our stabilizing compounds are also used to advantage with mordants in dye-image receiving sheets for dye diffusion transfer processes such as are described in French Patent 75,676, dated June 19, 1961. Mordant receiving sheets in which our compounds can be used to advantage are described in French Patent 1,361,293, dated Apr. 6, 1964. When the diifusible-image dyes are mordanted in such receiving scheets containing our stabilizer compounds, they exhibit marked improvement in light stability.

Usually emulsions containing our stabilizer compounds are coated on photographic supports in the form of multilayer color photographic elements wherein at least three differently sensitized emulsion layers are coated over one another on the support. Usually the support is coated in succession with a red-sensitive layer, a green-sensitive layer, and a blue-sensitive layer either with or without a Carey Lea filter layer between the blue-sensitive and green-sensitive layers. The three differently color sensitized layers may be arranged in any other order over one another that is desirable; however, the Carey Lea filter layer (i.e., yellow colloidal silver) would not be put over the blue-sensitive layer. Preferably, these light-sensitive layers are arranged on the same side of the support.

In general, our stabilizing agents are used in quantities ranging from 0.25 mole to 20 moles of stabilizer per 1 mole of coupler used (or per 1 mole of dye produced). The preferred range is from 1 mole to 5 moles of stabilizer per mole of coupler (or per mole of dye produced).

Our invention is further illustrated by the following examples.

Example 1 Single layer gelatin silver bromoiodide coatings con taining magenta-image-forming coupler, 1-(2,4-dimethyl- 6-chlorophenyl) 3 {3-[ot-(3-pentadecylphenoxy)butyrarnido] benzamido}-5-pyrazolone, and stabilizer compound in coupler solvent, tri-o-cresylphosphate, were made for our stabilizer compounds 1, 3, 4, 5, 6 and 7, respectively. A control coating containing no stabilizer compound was also prepared. Each of these coatings contained 44 parts by weight of gelatin, 16 parts by weight of silver, 5 parts by weight of coupler, 2 parts by weight of stabilizer, and 5 parts by weight of coupler solvent. Strips of the above mentioned coatings were each given -second exposure on a 1B intensity scale sensitometer and processed to color negatives according to the following process:

4-amino-3-methyl-N-ethyl-N-fl- (methanesulfonamido)ethylaniline sesquisulfate hydrate g 5.0

Sodium carbonate monohydrate g 50.0 Sodium bromide g 0.2 Water to 1 liter.

pH to 10.75.

These processed strips containing the magenta dye images were then subjected to a 10-day average north skylight exposure using an area of the dye image which had an original density of 1.2, i.e., as measured by a color densitometer. The amount of dye loss due to the 10-day exposure was then determined for each of the coatings by measuring the dye density in the exposed area, again with the color densitometer, after said exposure.

The precent improvement in light stability of the image dye in each of the coatings relative to that of the image dye in the control coating No. 1 (i.e., containing no stabilizer) is given in the following Table I.

TABLE I Percent improvement in light stability Example 2 Single layer gelatin silver bromoiodide coatings containing an image-forming coupler and stabilizer compound No. 1 in coupler solvent, tri-o-cresylphosphate, were made using the couplers given in the following table, respectively. A control coating containing no stabilizer was made using each of the couplers, respectively. Each of these coatings contained 50 parts by weight of gelatin, 15 parts by weight of silver, and 5 parts by weight of coupler solvent. The amount of stabilizer compound No. 1 and the amount and identity of the particular couplers used in each of these coatings is given in the following Table II. In each of these coatings, the coupler and stabilizer compound were dispersed together in the coupler solvent.

TABLE II Stabilizer Coating No. (compound Coupler used 1 (control). None parts by weight ofmagenta-image-torming coupler, 1-l2,6-dichloro-4 [a-(3-pentadecylphenoxy) -butyramido]phenyl} -3- (2, t-dichloroanilino)-5-pyrazolone. 2 4 parts by Same as No. 1 above.

Weight. 3 (control) None parts by weight of yellow-image-forming coupler, a-{B-[oz-(Z, 4-di-t-amylphenoxy) butyramido1-b enzoyl] -2-methoxy-acetanilide. 4 5 parts by Same as No. 3 above.

weight. 5 (control).. None 5 parts by weight of cyan-image-lormmg coupler, 1-hydroxy-N-[ -(2, t-di-t-amylphenoxy) butyl]2-naphthamide.

6 3 parts by Same as No. 5 above.

weight.

7 (control). None 5 parts by weight of magenta-1mage-iorming coupler, 1-(2, 4, G-trichlorophenyl) 3- {4-[11-(2, 4-di-t-amylphenoxy) butyramido]-anilino} -5-pyrazolone.

8 4 parts by Same as No. 7 above.

weight.

9 (control) None 5 parts by weight of magenta-imageforming coupler, 1-{4-[y-(2,4-d1-t-amylphenoxy)butyramido1-phenyl} -3-ethoxy fi-pyrazolone.

10 5 parts by Same as No. 9 above.

weight.

11 (control)... None.--.. 5 parts by weight of magenta-image-forming coupler, 7-[a-(3-pentadeeylphenoxy) butyramido1-3-indazolinone.

12 3 parts by Same as No. 11 above.

weight.

TAB LE III Percent improvement in light stability of the image dyes relative to that of the image dye in the control Coating No.

The color developer solution used to develop this coating and its control contained 4-amino-3-methoxy-N ethyl-N-(B-hydroxyethyl) aniline in place of the p'phenylenediantine given in the developer solution of Example 1.

Example 3 A single layer gelatin silver bromoiodide coating containing 1 part by weight of stabilizer Compound No. '1 in a solvent mixture of 2 parts by weight of tri-o-cresylphosphate and 1 part by weight of 2,2'-methylenebis[6- l-rnethylcyclohexyl)-4-methylphenol] was made. This coating also contained 14 parts by weight of gelatin and 10 parts by weight of silver. A control coating containing no stabilizer compound was also prepared. These coatings demonstrate the utility of our stabilizer compounds in coatings containing no coupler.

Exposed samples of the above mentioned coatings were processed to color positives by developing them first in a black-and-white type developer, then reexposing the residual silver halide (i.e., positive image) and developing them in a color developer solution similar to that given in Example 1 above except that the solution also contained the magenta-image-forming coupler, 1-(2,4,6-trichlorophenyl)- 3-(4-nitroanilino)-5-pyrazolone. The processed strips were then subjected to light fade exposures as described in Example 1.

The image dye in the coating containing our stabilizer compound exhibited a markedimprovement in light stability over that of the image dye in the control coating (i.e., containing no stabilizer compound).

The following preparation will illustrate the synthesis of our stabilizer compounds.

Compound No. '1, 2,2-dimethyl-4-isopropyl-7-t-butyl-6- hydroxychrornan: to a mixture of 40 ml. of acetic acid, 10.7 g. of t-butylhydroquinone, and 1 g. of zinc chloride, there was added 7.1 g. of 2,S-dimethyl-2,4-hexadiene over a 2-hour period. During the addition, and for 1 hour thereafter, the reaction mixture was maintained at C. Then 2 drops of concentrated sulfuric acid were added and heating continued for 5 minutes. The mixture was added to 200 ml. of water and on cooling a light yellow solid formed. This solid was recrystallized from aqueous ethanol to yield 15 g. of White product, M.P. l46-l49 C.

The other stabilizers of our invention are prepared to advantage by a similar method using the appropriate intermediates. For example, Compond No. 2 was prepared by reacting t-butylhydroquinone with 2-methyl- 2,4-pentadiene; Compound No. 5 was prepared by reacting t-butylhydroquinone with Z-methyl-butadiene; Compound -No. 3 was prepared by reacting isopropylhydroquinone with 2-methyl-2,4-pentadiene; Compound No. 4 was prepared by reacting isopropylhydroquinone with 2,5-dimethyl-2,4-hexadiene; Compound No. 6 was prepared by reacting t-octylhydroquinone with 2,5-dimethyl- 2,4-hexadiene; and Compound No. 7 was prepared by reacting t-octylhydroquinone with 2-methyl-2,4-pentadiene in accordance with the procedure given in Example 1. Similarly, any of the other compounds of our invention are prepared by the method of Compound 1 using the appropriate intermediates.

Although the alkyl group on the position ortho to the hydroxy group of our stabilizer compounds may be either straight or branched chain, the branched chain groups such as, for example, t-butyl, isopropyl, t-octyl, are preferred.

When our stabilizer compounds are used according to our invention in multilayer, three-color coatings containing cyan, magenta, and yellow image-dye-forming couplers, improvements in the light stability of the image dyes similar to those described above are obtained.

In addition to improving considerably the light stability of the image dyes in single layer or multilayer color photographic coatings for producing three-color or other dye images, our stabilizer compounds can be employed without producing adverse photographic effects on the emulsions of said couplers, and without becoming colored when coatings containing them are put through the processing solutions such as developers, fixing baths, bleaching baths, etc.

Our new and improved stabilizer compounds can be dispersed readily in image-forming layers either with or without coupler and without causing adverse effect on the coupler reactivity, and without causing interaction with either fresh or oxidized color developing agents.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

We claim:

'1. A hydrophilic colloid layer containing a color photographic dye image, said layer containing at least one 6-hydroxychroman dye-stabilizing compound, said compound having an alkyl group attached to one of the positions ortho to the 6-hydroxyl group of said compound and hydrogen atoms attached to the remaining two open positions ortho and meta to said hydroxyl group.

2. A hydrophilic colloid layer containing a color photographic dye image, said layer containing at least one 6-hydroxychoman dye-stabilizing compound having the formula:

wherein R and R each represents a member selected from the group consisting of the hydrogen atom and an alkyl group such that only one of the groups is an alkyl group; R R and R each represents a member selected from the class consisting of the hydrogen atom and an alkyl group.

3. A dye-image-forming silver halide emulsion layer comprising a film-forming hydrophilic colloid containing at least one 6-hydroxychroman dye-stabilizing compound, said compound having an alkyl group attached to one of the positions ortho to the 6-hydroxyl group of said compound and hydrogen atoms attached to the remaining two open positions ortho and meta to said hydroxyl group.

4. A dye-image-forming silver halide emulsion layer comprising a film-forming hydrophilic colloid containing at least one 6-hydroxychroman dye-stabilizing compound having the formula:

wherein R and R each represents a member selected from the group consisting of the hydrogen atom and an alkyl group such that only one of the groups is an alkyl group; R R and R each represents a member selected from the class consisting of the hydrogen atom and an alkyl group.

5. A light-sensitive hydrophilic colloid-silver halide emulsion layer containing 2,2-dimethyl-4-isopropyl-6- hydroxy-7-t-butylchroman.

6. A light-sensitive hydrophilic colloid-silver halide emulsion layer containing 2,2,4-trimethyl-6-hydroxy-7- isopropylchroman.

7. A light-sensitive hydrophilic colloid-silver halide emulsion layer containing 2,2-dimethyl-4,7-di-isopropylfi-hydroxychroman.

8. A light-sensitive hydrophilic colloid-silver halide emulsion layer containing 2,2-dimethy1-6-hydroxy-7-tbutylchroman.

9. A light-sensitive hydrophilic colloid-silver halide emulsion layer containing 2,2-dimethyl-4-isopropyl-6- hydroxy7-t-octylchroman.

10. In a multilayer multicolor element containing silver halide emulsions and incorporated color-forming couplers, the improvement comprising the incorporation of a 6-hydroxychroman dye-stabilizing agent in at least one of said layers, said dye-stabilizing agent having an alkyl group attached to one of the positions ortho to the 6-hydroxyl group of said agent and hydrogen atoms attached to the remaining two open positions ortho and meta to said hydroxyl group.

'11. In a multilayer multicolor element containing silver halide emulsions and incorporated color-forming couplers, the improvement comprising the incorporation of a dye stabilizing agent having the formula:

wherein R and -R each represents a member selected from the group consisting of the hydrogen atom and an alkyl group such that only one of the groups is an alkyl group; R R and R each represents a member selected from the class consisting of the hydrogen atom and an alkyl group.

12. In an image-forming silver halide emulsion layer the improvement comprising the use of a 6-hydroxychroman dye-stabilizing agent, said dye-stabilizing agent having an alkyl group attached to one of the positions ortho to the 6-hydroxyl group of said agent and hydrogen atoms at tached to the remaining two open positions ortho and meta to said hydroxyl group.

13. In an image-forming silver halide emulsion layer the improvement comprising the incorporation of a dyestabilizing agent having the formula:

wherein R and R each represents a member selected from the group consisting of the hydrogen atom and an alkyl group such that only one of the groups is an alkyl group; R R and R each represents a member selected from the class consisting of the hydrogen atom and an alkyl group.

:14. A light-sensitive hydrophilic colloid-silver halide emulsion layer containing 2,2,4-trimethyl-6-hydroxy-7-toctylchroman.

References Cited UNITED STATES PATENTS 2,360,290 IO/1944 Vittum et al 96-56 2,421,811 6/1947 Smith et al. 260-3455 2,535,058 12/1950 Gleim et al. 260345.'5

NORMAN G. TORCHIN, Primary Examiner. M. R KELLY, Assistant Examiner.

US. Cl. X-R. 96-56 

